System pressure loss Worcester 24CDi BF

[Vossy1]

New to the forum and not a plumber/heating engineer so be kind 😀
I've been having a problem with pressure loss in my Worcester 24CDi BF. I have trawled the internet and tried various trouble shooting pointers but am now struggling, here's the scenario.

The problem is a long term one, as a example charged system to 1.5 bar last night 6pm this am 0 bar.
In the past I've just left it and continued to use the boiler with no issues. Yesterday I replaced a slow leaking auto air vent and thought my problem would be solved...fat chance! In the past I've replaced the prv as it also had a slow leak (detritus in seal seating area), I've also had the opportunity to inspect all rads in the system and associated pipework when having new floorboards laid.

I'm now starting to think there may be an internal leak or worse case a pinhole somewhere so I've just checked the expansion vessel by depressing the tyre type valve. I was expecting a hiss if under pressure or water if faulty but instead got neither.

I'm struggling now as though quite handy I have a distinct lack of knowledge in this area..
Is it possible for the boiler to work normally as it is/has been doing with no pressure in the expansion vessel?
Is it possible for the pressure to be lost over time to a slow leak, the boiler is quite old?
I can try recharging the ev but is it worth it?

Any help would be much appreciated ;-)

 

[skippy]

I've got exactly the same problem at the moment in a keston boiler - diagnosed as a hole in the expansion vessel diaphragm (apparently obvious to tell as the expansion vessel was full of water when the boiler was off)

I was also told that it might be PRV, leaking under the floor, pinhole until the engineer checked the ev.

I haven't had it fixed yet - am hoping to in the next week. Will repost and let you know if it fixes it.

* I'm not a heating engineer either so had to actually read up on what the EV does.
"The expansion vessel is a metal container divided in two by a rubber diaphragm. One side is connected to the pipe work of the heating system and therefore contains water. The other, the dry side, contains air under pressure and you will find a car-tyre type valve for checking pressures and adding air.

When the heating system is empty or at the low end of the normal range of working pressure the diaphragm will be pushed against the water inlet. As the water expands so the diaphragm moves compressing the air on its other side and giving rise to a moderated increase in pressure that you can see on the pressure gauge."

 

[Howsie]

Your expansion vessel needs replacing.

 

[Vossy1]

Thanks for the feed back guys, much appreciated ;-) Whilst being quite handy myself this is a job for a heating engineer, especially getting the ev out :-0

 

[Barry98]

Thanks for the feed back guys, much appreciated ;-) Whilst being quite handy myself this is a job for a heating engineer, especially getting the ev out :-0

we have a " i need a plumber " section on here stick a request in there , strong possibility there's a member on here near you

 

[Centralheatking]

Why dont we have a section totally dedicated to Combis and pressure loss - it must be
around 10-15% of probs reported - and its a really big prob to owners and quite obviously
tradesman as well -

centralheatking